Per- and Polyfluoroalkyl Substances (PFAS) in Urbanized Section of the Delaware River Watershed: Risk Assessment and Geographical Distribution

This study investigates the prevalence and risk assessment of per- and polyfluoroalkyl substances (PFAS) in the Delaware River, analyzing 23 water samples collected in 2019 and 2021. The concentration of prevalent chemicals (PFTeDA, PFTrDA, and PFDS) were significantly reduced from average values of 461.67 ng/L, 447.63 ng/L, and 137.10 ng/L between 2019 and 2021, as determined by the analysis of PFAS levels. The most prevalent chemicals in 2021 were PFOA and 6:2FTS, with average concentrations of 5.37 ng/L and 4.23 ng/L, respectively. Based on EPA guidelines, the study assessed environmental and human health hazards from the compounds in the source of drinking water samples using the risk quotient (RQ) and Hazard Index (HI). Following 2016 EPA guidelines, 75% of 2019 and 2021 source water samples had medium risk levels for combined PFOA and PFOS, while the rest were low risk. The RQ of the samples based on 2022 EPA guidelines showed high risk in 92.3% and 38.4% of 2019 collected samples for PFOA and PFOS, respectively. Based on their RQs, all the source water samples in 2021 showed high-risk levels of PFOA. Additionally, the 2023 EPA Hazard Index (HI) approach showed that PFBS, PFHxS, PFNA, and HFPO-DA do not exceed the threshold value. These results underscore the necessity of continuous monitoring and regulation to reduce the adverse effects of PFAS contamination on the Delaware River ecosystem and public health.